1. Field of the Invention
The present invention relates to the field of hygiene. More specifically it relates to the monitoring of airborne contaminants inside structures, including but are not limited commercial, industrial, and residential buildings, as well as public transportation, airplane, train, ship, and the like.
2. Background Information
The measurement of indoor aerosols is a key activity in diagnosing indoor air quality problems in buildings, residences, public offices, manufacturing sites, public transportation and other places where people spend extended time indoors. These aerosols can vary in composition and concentration by location, geography, time-of-day and other factors. Identifying the size distribution of the indoor aerosol is very important in diagnosing and fixing indoor air quality problems. Size is considered a strong function of the origin of the contaminant. For example, cigarette smoke particles are generally less than 1 micron in size where most pollens range from 5-50 microns in size.
Light scattering instruments have been used for the past 20 years to quantify the amount of aerosol by providing a single number that can be used to estimate the total concentration in units of mass/volume, e.g. micrograms per cubic meter. These instruments are typically expensive, heavy, and provide only a simple snapshot of the distribution of particles in an aerosol.
3. Terminology
Throughout the remaining specification, including the claims, usage of the term “particle” is intended to include aerosols found in buildings, residences, mass transportation vehicles etc., such as: general particulate matter, fine dust from building materials, plants and animal allergens, mold and mildew spores, the inflammatory, toxic or mutagenic residue from the growth of mold or gram negative bacteria, man-made pollution such as exhaust from fuel combustion, and any other matter suspended in the ambient air in the form of an aerosol that will scatter light. Further, the use of the term “nephelometer” applies to a general class of instruments that use scattered light measurement to quantity the amount and provide information on the size of particles in an indoor aerosol.